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The stress analysis of High Temperature Superconducting (HTS) magnet for a 600 kJ superconducting magnetic energy storage (SMES) is discussed. Findings reveal that the HTS magnets are stable in radii stress and hoop stress.

A 600 kJ Superconducting Magnetic Energy Storage System (SMES) project with High Temperature Superconductor (HTS) started as a national project in Korea. The HTS model coils were designed and fabricated for a preliminary test prior to the creation of a full scale prototype. Single reinforced BSCCO-2223 wires were used for the model coils and the operating temperature was decided to be 20K. Even though an SMES is not an AC-powered device, time-varying currents during the charging and discharging periods lead to the generation of time-variation magnetic fields applied to the model coils and the generation of AC loss. In this paper, AC loss and the temperature distribution of model coils are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Development of a 600 kJ Superconducting Magnetic Energy Storage (SMES) system is in progress by Korean Electric Research Institute (KERI). High-temperature superconducting (HTS) wires arc going to be used for the winding of the system. The design of the HTS windings for the system is presented in this paper. We considered BSCCO-2223 wire for the HTS windings. The operating temperature of the winding was decided to be 20 K which will be accomplished by conduction cooling method using cryo-coolers. Auto-Tuning Niching Genetic Algorithm was adopted for an optimization method of the HTS magnets in the SMES system. The objective function of the optimal process was minimizing the total amount of the HTS wire. We also estimated the AC loss which can be generated in the discharge period. These HTS windings are going to be applied to the SMES system whose purpose is the stabilization of the power grid. [ABSTRACT FROM AUTHOR]

A 1 MVA single phase high temperature superconducting (HTS) transformer was manufactured and tested. The rated voltage of primary and secondary of HTS transformer are 22.9 kV and 6.6 kV respectively. BSCCO-2223 HTS tape was used for HTS windings of 1 MVA HTS transformer. In order to reduce AC loss generated in the HTS winding, the concentrically arranged winding was adopted to 1 MVA HTS transformer. Single HTS tape for primary windings and 4 parallel HTS tapes for secondary windings were used considering the each rated current of the HTS transformer. A core of HTS transformer was fabricated as a shell type core made of laminated silicon steel plate. And a GFRP cryostat with a room temperature bore was also manufactured. The characteristic tests such as no load test, short circuit test and several insulation tests were performed at 65 K using sub-cooled liquid nitrogen. Through these test results, the validity of design of HIS transformer was ascertained. [ABSTRACT FROM AUTHOR]

AC loss is one of the important parameters in HIS (High Temperature Superconducting) AC devices. Among the HTS AC power devices, the transformer is an essential part in electrical power system. But, AC loss is one of the most serious problems of the HIS transformer, especially with pancake windings, because high alternating magnetic field is applied perpendicularly to the surface of BSCCO wire in HIS windings of that, comparing with the other HTS AC power devices. For the reason above the calculation of AC loss generated in the HTS windings should be carried out in advance when designing the HTS transformer. In the paper we performed study for optimization of winding design to minimize the magnetization loss of HTS winding such as the spaces between pancake windings and operating temperature of HIS wire. The calculation of the AC loss was accomplished by 2-dimensional Finite Element Method. [ABSTRACT FROM AUTHOR]

A 1 MVA single phase high temperature superconducting (HTS) transformer was fabricated and a part of experimental test for characteristics of the transformer was performed. The rated voltages of primary and secondary of the HTS transformer are 22.9 kV and 6.6 kV respectively. BSCCO-2223 wire was used for HTS windings whose shapes are double pancake arranged reciprocally. Single HTS wire for primary windings and 4 HTS wires for secondary windings were used considering the rated current of the transformer. Four HTS wires in secondary windings were transposed at the connection between double pancakes 3 times. The electrical insulation and transport current test were performed at 77 K using liquid nitrogen. The rest of the test for the characteristics of the transformer is in progress. [ABSTRACT FROM AUTHOR]

It is common practice to wind coils in pancake shape for conventional high voltage transformers because of electrical insulation problems. In HTS superconducting transformers, the perpendicular component of magnetic flux density (B[sub r]) applied to HTS tapes of pancake windings becomes larger than that of solenoid winding, thereby decreasing the critical current in the HTS tapes. This paper introduces several methods to reduce B[sub r] applied to the HTS tapes in the transformer with double pancake windings by changing winding arrangements and the relative permeability of flux diverters. We have conducted a winding design for a single-phase 1 MVA 22.9 kV/6.6 kV HTS transformer. The magnetic field in the spaces occupied by the windings and its vicinity was numerically simulated. We observed a change of B[sub r] due to various gap arrangements of high voltage and low voltage windings and various reciprocal arrangements. We also observed a change of B[sub r] on the HTS tapes due to variation of relative permeability of flux diverters placed between the high voltage winding and the low voltage winding. [ABSTRACT FROM AUTHOR]

Describes the construction and test results of a ten-kilo-volt-ampere single phase high temperature superconducting (HTS) power transformer. Use of double pancake windings with BSCCO-2223 HTS tape and glass fiber reinforced plastic cryostat with room temperature bore; Finding that leakage reactance is much higher than that of other HTS transformers because of the large air gap between the core and the windings.

Describes the fabrication and testing of a single-phase power transformer with windings made of high critical temperature superconducting tapes. Transformer design; Magnetic field distribution; Short circuit tests performed; Overload capability and characteristics.

Describes the development of a 100 kVA three phase superconducting transformer. Fundamental characteristics of the transformer; Transformer cores as made of amorphous films; Immersion of films in liquid helium with transformer windings for simplifying the structure.

A 1 MVA transformer using BSCCO-2223 high T[sub c] superconducting (HTS) tapes was designed. The rated voltages of each sides of the transformer for primary and secondary are 22.9 kV and 6.6 kV respectively. Double pancake HTS windings, which have advantages of insulations and distribution of high voltage, were adopted. Four HTS tapes were wound in parallel for the windings of !ow voltage side. Each winding was composed of several double pancake windings and four parallel conductors of secondary winding were transposed in order to distribute the currents equally in each conductor. The core of the transformer was designed as a shell type core made of laminated silicon steel plate and the core is separated from the windings by a cryostat with a room temperature bore. Configuration of the cryostat made of nonmagnetic and nonconducting material and a liquid nitrogen sub-cooling system were used in order to maintain the coolant's temperature of 65 K. [ABSTRACT FROM AUTHOR]